Purpose of the present research project is to study a new in-vivo test for abnormal platelet function and to study the effect of certain drugs on clinical bleeding. This is a randomized clinical trial of a new in-vivo test of platelet function known as the bleeding volume test(BVT)which relies on an on-line measurement system. This trial will assess the sensitivity and specificity of the new BVT by studying the effects of aspirin which is known to affect platelet function in-vivo. This is not a clinical trial of drugs. This is a clinical trial of a novel in-vivo on-line laboratory test.

The BVT measures the total volume of blood in the discrete blotches of blood on the blotter paper during the BT test and thus the BVT gleans valuable additional information from the bleeding time test (BTT)procedure. We hypothesize that the BV test will be a more accurate, specific and sensitive test for diagnosing platelet function abnormalities and for detecting a person's bleeding tendency compared to the BTT, and commercially available in-vitro platelet function tests.

Detailed Description

Purpose of the present research project is to study a new in-vivo test for abnormal platelet function and to study the effect of certain drugs on clinical bleeding. This is a randomized clinical trial of a new in-vivo test of platelet function known as the bleeding volume (BV) test which relies on an on-line measurement system. This trial will assess the sensitivity and specificity of the new BV test by studying the effects of aspirin which is known to affect platelet function in-vivo. This is not a clinical trial of drugs. This is a clinical trial of a novel laboratory test. The BV test results will be compared to the results of two commercially available platelet function tests (the VerifyNow test and the PFA-100 test) which requires 10 ml of blood taken from a peripheral vein.

The bleeding volume test is an extension of the classic Ivy Bleeding Time Test (BTT). The BTT, an in-vivo test for an abnormal bleeding tendency, involves making a small standardized cut in the skin and measuring the duration of bleeding. We hypothesize that measuring both the volume of blood lost (BV) and the BT will to provide a more useful test. The BV test is expected to provide an improved in-vivo technique for 1) investigating the effects of drugs on platelet function and 2) diagnosing diseases of abnormal platelet function such as von Willebrand disease (vWD), 3) identifying patients who are aspirin-resistant in the sense that they do not benefit from the beneficial effects of aspirin in preventing thromboembolic disease (heart attack and stroke), 4) providing insight into the effects of antithrombotic drugs such as clopidogrel, lidocaine and statins (HMG-CoA reductase inhibitors). The BV test will provide an inexpensive diagnostic test and improve patient care.